Thread-controlled stopping device for sewing machines



Dec. 3, 1929. J, GAIL 1,738,142

THREAD CONTROLLED STOPPING DEVICE FOR SEWING MACHINES Filed Oct 2. 19262 She ets-Sheet 1 Jhw]? Gew'l/ faiw, M

w- 3, 1929. J. F. GAIL 1,73s,i42

THREAD CONTROLLED STOPPING DEVICE FOR SEWING MACHINES Filed on. 2, 19262 Sheets-Sheet 2 him/,MpWf

Watentd a UNITED STATES PATENT OFFICE JOHN l. GAIL, OF EVANB'ION,ILLINOIS, AISIGNOB 'I'O SIMMONS COMPANY, 01 NEW YORK, N. Y., A.CORPORATION OF DELAWARE THBEAD-OONTBOLIJED STOPPING DEVICE FOR SEWINGMACHINES Apullcation fled October 2 1926. Serial No. 189,048.

a su ply of thread.

e objects of the invention are to provide means controlled by the supplyof thread or other sewing medium which will automatically stop operationof the sewing machine when 10 the thread is broken, comes to an end, orthe supply thereof is exhausted and to provide means of the abovedescribed character which will be controlled by the normal tension onthe thread. Other objects are to provide means of the above describedcharacter which will be simple in construction and operation; to providesuch means which will not readily become out of order and consequentlyinoperative; to provide such means which will require practically-noattention whatever on the part of the operator and, in general, toprovide an improved device of the class described. Other objects andadvantages will become apparent when reference is had to the followingspecification when considered in connection with the accompanyingdrawings wherein I have illustrated a selected embodiment of myinvention and in which Figs. 1 and 2 are end and side elevationsrespectively of a portion of a sewing machine head showing my improveddevice applied thereto. a

Fig. 3 is an elevation of a clutch control and brake mechanism which maybe used for transmitting the driving power to the sewing machine andwhich is adapted to be controlled by my improved device.

Fig. 4is an elevation having certain parts broken away to more clearlyillustrate con- %truction and corresponds to a portion of ig. 1. I

Fig. 5 is an end elevation of the left end of Fig. 4.

Fig. 6 is a plan, and

Fig. 7 is a section on the line 7-7 of Fig. 4.

Referring now to the drawings, a sewing machine" head of conventionaltype is indicated at 10. The head 10 is provided with the usualreciprocating needle bar 11 to which is secured a needle 12 in anysuitable manner.

The mechanism for reciprocating the needle bar 11 forms no part of thepresent invention, but maybe of any suitable construction and thereforeneed not be specifically described or illustrated.

At the top of the head 10, I mount an electric switch 13 which isincluded in an electric circuit adapted to supply electric energ to apair of clutch controlling magnets 14 ig. 3.) The clutch mechanismincludes a pulley 15, clutch collar 16 and clutch lever 17 which ispivoted at 18 to a stationary part of the machine. The clutch lever 17is provided with suitable means for engaging the collar 16 to engage ordisengage the clutch and is also provided with a pm 19 which is adaptedto be engaged by a pivotally mounted arm 20 to hold the clutch inengaged position. A spring 21 connected between the end 22 of the arm 20and a suitable connecting eye 23 on the supporting frame is adapted tonormally hold the arm 20 in engagement with the pin 19. The magnets 14:when energized by an electric current are adapted to pull the arm 20down through the armature 24 whereby the clutch may be released bysuitable spring 25 connected to the lower end 26 of the arm 17. Anotherelectric switch 27 is included in the circuit with the switch 13 andmagnets 14 and is arranged to break the circuit as soon as the clutchhas been disengaged.

The present invention does not include the above described clutchstructure per se and, therefore, will not be more specificallydescribed, but a more complete description of this structure may be hadby reference to my co-pending application for Machine for making spiralsprings, Serial No. 557,121, filed April 28, 1922.

The switch 13 mounted at the top of the sewing machine head 10preferably comprises a bracket-frame 30 having an attaching car 31adapted to be seated against a portion of the sewing machine head andsecured thereto by suitable means such as screws as clearlyshown inFig. 1. A block 32 of insulating material is disposed within the framebetween the upper leg 33 and lower leg 34 and is secured by suitablemeans such as screws 35 to the upwardly extendingback portion 36 of theframe; I A air of contact members 37 and 38 are secure to the insulatingblock 32 in such a manner that they are insulated from each other and inthe present instance comprises screws 39-39 and 40-40 respectively whichthreadedly engage suitable a 'ertures in the block. Provision is made orconnecting the respective contact plates to wires of the electriccircuit in which the switch is connected and comprises plugs ductingelectricity. The plugs 41 and 42 are preferably split at their outerends to render them somewhat springy or compressible so that they may beslightly compressed by means of suitable plu sockets 44 as best shown inFig. 1, where y the sockets will be retained on the plugs and will makegood contact therewith.

The contact members 37 and 38 are also each provided with an outwardlyextending resilient ear 45 and 46 respectively which areadapted to beconnected by means of a metal cylinder or collar '47 which is normallymaintained below the ears and out of contact therewith. The contactcollar 47 is beveled at its upper end so as to facilitate entrancebetween theears 45 and 46, and is mounted on a suitable bushing 48 ofinsulating material fixed on a vertical rod 49. The rod 49 is slidablymounted in suitable bearing apertures 50-50 in the upper and lower legs33 and 34 .of the bracket frame. Retrograde movement of the rod 49 withresulting breakage of the circuit is prevented by friction due topressure of the ears 45 and 46 upon the .cylindric portion of the collar47. The upper end of the rod 49 is preferably bent over and turneddownwardly as best shown in Figs. 4 and 5 to provide a downwardlyextending portion 51. It will be' apparent that when the rod 49 is movedupwardly a sufiicient distance, the metal collar 47' will assume aposition between the ears 45 and 46 of the contact plates 37 and 38respectively and will be effective to establish electrical connectiontherebetween.

. i I prefer to actuate the switch mechanism by means associated withthe reciprocating I needle bar 11 and controlled by tenslon on thethread T, which is used as a sewing medium. As best shown in Figs. 4, 5,and 6, I mount a bracket 52 on the top of the needle bar 11 by anysuitable means such as inter-engaging threaded stud and aperture onthebar and in the bracket respectively as shown at 53 in Fig. 4.Betweenthe bracket 52 and the top of the bar 11 is interposed a threadguide 54 which preferably comprises a-wire member forming a complete 100or eye as indicated at 55 and a downward y facin open hook portion 56,said eye and hook eing spaced apart as clearly shown in Fig. 6.

The thread used in sewing is guided from the usual supply spindlethrough the eye 55 and the hook 56. Intermediate the eye and hook, thethread engages one leg 57 of a bell crank lever which is plvotallymounted as indicated at 59 in the bracket'52. The thread engages the leg57 preferably by passing through a suitable aperture in the end thereofas indicated at 60. After the thread leaves the hook 56, it is threadedthrough a tension or friction device which tends to maintain the threadunder normal tension by preventing the needle from pulling too muchthread from the supply spindle on any one stroke whereby the threadwould otherwise become loose and would not be under any appreciabletension. Tension on the thread is alsopartly produced by providing somemeans for holding against withdrawal of the thread from the supplyspindle. In cases Where a spool of thread is used and the spool iscaused to rotate as the thread is pulled therefrom, this holding meansmay be applied to prevent too free a rotation of the spool.

- The first mentioned friction or tension device comprises an uprightbar 61 which is secured to the head by suitable means and is relativelystationary. In the present instance, I prefer to mount the bar 61 soasto provide a certain amount of vertical adjustment and I mayconveniently do this by providing its lower end with a slot as indicatedat 62, (Fig. 1) through which the screw 63 may be passed into threadedengagement with a portion of the head 10. The-scrcw 63 is adapted toclamp the bar 61.in the desired position of vertical adjustment. The bar61 is provided at its upper end with an overhanging hook portion 64whichis adapted to maintain a leaf spring member 65 in close proximityto the edge 66 of the bar at its upper end. The leaf spring 65 issecured at its lower end to the bar 61 by suitable means such as a screw67-. The thread passes between the edge 66 of the bar' and the opposingface of the leaf spring 65 and is thereby placed under a certain degreeof tension as it is drawn therethrough from the supply spindle. Anothermember 68 is also'mounted on the upper end of the reciprocating needlebar by being interposed betweenfthe bracket 52 and the said upperendand. isprovided with an outwardly extending ear 69- which isapertured as at 70 to fit over the bar Gland so as to be capable ofbeing moved'inaver tical direction relative to the bar as the needle bar11 is reciprocated.

It will be apparent that when the needle bar and needle are moved in adownward direction the thread may be pulled between the bar 61 andspring 65 as much as is necessary. It will also be apparent thatthe loopand hook 56 are effective to cause the thread to move downwardly betweenthe said bar andspring whereby no large amount of thread need be pulledfrom the supply spindle at any one stroke of the needle bar and alsowhereby no large amount of slack thread need be provided to permit thenecessary reciprocation of the needle bar. On the up stroke of theneedle bar the apertured plate 69 is effective to cause the threadbetween the bar 61 and spring 65 to also move up wardly with the needlebar. 1

The normal tension on the thread as it passes through the aperture inthe leg 57 of the bell crank 58, is suflicient to maintain the leg 57 ina down position against the pressure ot a spring pressed plunger 71which, together with the spring 7 2, is mounted in a suitable aperturein the bracket 52 as shown in Fig. l. It will be apparent that it thesupply of thread is exhausted or if the thread breaks at some pointbefore it passes all between the bar 61 and spring so that the normaltension on the thread is relieved,the spring 72 and plunger 71 will beeffective to raise the leg 57 of the bell crank 58 to a posi-- tionsuchas illustrated in dotted lines in Fig. t. It will be noted the pressureof the leaf spring65 on the thread against the face 66 of the bar 61 issullicient to prevent the spring pressed plunger 71 from moving the leg57 of the bell crank 58 upwardly and pulling the thread. between theleaf spring 65 and bar 61 from the needle. The bell crank lever 58 isprovided with another leg 73 which, in its normal position, when the leg57 is held down by the thread. will not engage the downwardly facing end51 of the rod 49. When permitted to assume its operative position asindicated in dotted lines, when the thread is broken and on its upstroke, the leg 73 will be effective to engage this downwardly facingend so that itwill raise the rod 49 and there by cause the metal collarl7 to establish electrical contact between the contact plates 37 and 38as above described. When the switch is thusfclo'sed and a circuitcompleted, the magnets 14: will be energized and the clutch caused to bedisengaged as above described.-

fWhen it is desired to re start the machine, the operator pushes downupon the upper end of the rod 49 to disconnect the contacts 45 and 46 shas to break the circuit of the control --magnet's'1 l, and subsequentlyeffects engagethe reason that even though the adjustment may be suchthat the le 73 barely engages the abutment 51 when t e thread is broken,

the inertia, due to the high speed of reciprocation, is effective tofling the rod 49 and associated parts upwardly with a force amplysuflicient to force the contact collar 47 between the contacts 45 and46. A further reason for which the device is well adapted foruse withmachines operating at a high speed is that the shape and dimensions ofthe bell crank 57 are, as best shown in Fig. 4, such that the center ofgravity of the bell crank lies substantially in a vertical plane passingthrough the center of the pivot. 59. The bell crank is thereby balancedon its pivot on the needle bar, and hence when the machine operates athigh speed, causing the needle bar to reciprocate rapidly, the bellcrank will not'fiutter on its pivot. If the bell crank were permitted toflutter, i. e., if it were unbalanced so that it would oscillate on itspivot, due to inertia resulting from the reciprocation of the needlebar, the leg 73 might possibly accidentally engage the abutment 51 andstop the machine, even though the sewing thread retained its normaltension.

1 have thus provided a sim 1e and efficient automatic stop mechanism orsewing machines whichstop mechanism is controlled by the tension on thethread, and being of relatively t'ew working parts is not likely tobecome out of order and inoperative. Practically the only attention thatneed be given the device is to reset the switch rod 49 and the bellcrank 58 when thread is rethreaded through the various guides so thatthe switch will not be closed on starting of the sewing machine unlessthe thread again breaks or otherwise loses its normal tension. 1 amaware that various changes in the construction and arrangement of myimproved device may be made without departing from the es sence of theinvention and I therefore reserve the rightto make such changes asfairly fall within the scope of the following claims which should beconstrued as broadly as possible, consistent with the state of the art.

I claim as my invention:

"'1. In combination, a sewing machine including a reciprocating needlebar having a needle secured thereto, means for guiding thread to saidneedle, power means for operating said sewing machine, and threadcontrolled means for shutting off said power means to stop the operationof the sewing 'lnachine'and comprising an arm movably mounted on saldreciprocating needle bar and having'means for engaging the thread beforethe thread reaches the needle whereby the arm is normally held ininoperative position, means for causing said arm to move into anoperative position when the tension on the thread is reduced, and meansactuated by engagement with said arm when in said passes on its way tothe needle, the normal tenoperative position for shutting off said poweroperating ,means.

2. In combination, .afsewing machine including ajreciprocating needlebar havin a needle secured thereto-and means for guiding thread undertension to said needle, power driving means for driving said sewingmachine, electroinagnetic means for disengaging said driving means tostop said sewing machine, an electric circuit including a switch forcontrolling said electromagnetic means, and means for actuating saidswitch when the normal tension on'the sewing thread is reduced andcomprising an arm pivotally mounted on said reciprocating needle bar andhaving an aperture through which the thread sion on said thread beingsuflicient to mainta-in said arm in an inoperative position, and

by said switch for "stopping the operation of.

said reciprocating bar, means said arm being adapted to move into anoperative' position for actuating said switch when said normal tensionis reduced.

3. In combination, a sewing machine including a reciprocating needle barhaving a sewing needle at one end, an electric switch mountedon saidsewing machine adjacent movably mounted on said bar and controlled bythe tension on the sewing thread for-actuating said switch and normallyheld in inoperative position by the thread, andmeans controlled thesewing machine.

4. In combination, a sewing machine including a reciprocating needle barhavinga sewing needle at one end and means for supplying thread undertension to said needle, and an electric switch mounted on the sewingmachine adjacent said reciprocating bar, an arm pivotally mounted onsaidreciprocating bar and having thread engaging means and switch operatingmeans, said arm being normally held in inoperative position by.engagement with the thread and being adapted to move to an operativeposition for actuating said switch when the tension on the thread isreduced a considerable amount, and means controlled by said switch forstoppingoperation of the sewing machine.

5. The combination of a sewing machine head including a reciprocatingneedle bar, a

two position shifting trip member actuated by the machine in unison withsaid needle bar, the position of said trip member being controlled bythetension on the sewing medium, a two position switch actuatedby themachine through said trip'member and means associated with the switchfor automatically stopping the machine when the switch is actugged bythe machine through said trip memwith and controlled by the tension onthe sewing medium, a two position switch actuated by the machine throu hsaid tri member and means associated wit the switch for automaticallystopping the machine when the switch is actuated by the machine throughsaid trip member.

7. The combination of a sewing machine, an electrically operatedmechanism for stopping the machine, and means associated with anactuated part of the sewing machine mechanism so as to be actuated bythe movement thereof and controlled by the tension on the sewing mediumfor controlling an electric circuit for actuating said electricallyoperated mechanism.

8. In combination, a sewing machine including a reciprocating needle barhaving a needle at one end, adapted to effect stitching with thread orthe like, power means for operating the sewing machine, means forstopping the operation of the sewing machine by said power means, meanscarried by the needle bar and controlled by the normal tension on thesewing medium for controlling said stopping means, said threadcontrolled means comprising a two position bell crank pivotally mountedon said reciprocating needle bar so as to be substantially balanced onits pivot, thereby to prevent fluttering of the bell crank as anincident to reciprocation of the needle bar, said'bell crank beingnormally held in one position by the tension on the sewin medium, andmeans for shifting said bell crank to its second position so as to beeifective to actuate said stopping means when the tension on said sewingmedium is reduced.

9. In combination, a sewing machine including a reciprocating needle barhaving a needle at one end adapted to effect stitching with thread orthe like, power means for operating the sewing machine, means forstopping the operation of the sewing machine by said power means, meanscarried by the needle bar and controlled by the normal tension on thesewing medium for controlling said stopping means, "said controllingmeans including a member movably mounted on said needle bar,reciprocated in unison therewith and having a portion engaged by thesewing medium for normally holding the control ling means out ofoperative position, and

guiding means for the sewing medium,

JOHN F. GAIL.

6. The combination of a sewing machine 4 head including a reciprocatingneedle bar, a

two position shifting trip member carried by said needle ba reciprocatedin unison there-

